Biomedical subjects

J A Verhaar

Publications and source records attributed to J A Verhaar.

At least 19 recordsLinked to original sources

PubMed2001

Monoclonal antibody 11-fibrau: a useful marker to characterize chondrocyte differentiation stage.

The aim of this study was to determine the feasibility of discriminating between differentiated and dedifferentiated chondrocytes by using the Mab 11-fibrau. Mab 11-fibrau did not bind to differentiated chondrocytes in cartilage of human knee joint, auricle, or nasal septum. During monolayer culture, when cells dedifferentiate, the number of 11-fibrau positive cells gradually increased and reached up to 100% after 4 passages. When differentiated chondrocytes were cultured in alginate, most (90--95%) of the cells remained 11-fibrau negative, in accordance with previous studies demonstrating that differentiated chondrocytes cultured in alginate keep their phenotype. Dedifferentiated (11-fibrau positive) cells were subjected to different redifferentiation regimes. As a well-known fact, cultures in alginate in medium where FCS was replaced by IGF1 and TGF beta 2 results in increased collagen type II formation, indicative for redifferentiation. However, the cells remained 11-fibrau positive, suggesting they are not (yet) fully redifferentiated. On the other hand, when dedifferentiated cells (after 4 passages in monolayer culture) were seeded in a biomaterial and implanted subcutaneously in a nude mouse, the newly formed cartilage matrix contained collagen type II and the 11-fibrau staining on the cells had disappeared. Our results indicate that 11-fibrau may be a reliable and sensitive marker of chondrocyte phenotype.

Animals↗

PubMed2001

Trabecular bone's mechanical properties are affected by its non-uniform mineral distribution.

The bone remodeling process takes place at the surface of trabeculae and results in a non-uniform mineral distribution. This will affect the mechanical properties of cancellous bone, because the properties of bone tissue depend on its mineral content. We investigated how large this effect is by simulating several non-uniform mineral distributions in 3D finite element models of human trabecular bone and calculating the apparent stiffness of these models. In the 'linear model' we assumed a linear relation between mineral content and Young's modulus of the tissue. In the 'exponential model' we included an empirical exponential relation in the model. When the linear model was used the mineral distribution slightly changed the apparent stiffness, the difference varied between an 8% decrease and a 4% increase compared to the uniform model with the same BMD. The exponential model resulted in up to 20% increased apparent stiffness in the main load-bearing direction. A thin less mineralized surface layer (28 microm) and highly mineralized interstitial bone (mimicking mineralization resulting from anti-resorptive treatment) resulted in the highest stiffness. This could explain large reductions in fracture risk resulting from small increases in BMD. The non-uniform mineral distribution could also explain why bone tissue stiffness determined using nano-indentation is usually higher than finite element (FE)-determined stiffness. We conclude that the non-uniform mineral distribution in trabeculae does affect the mechanical properties of cancellous bone and that the tissue stiffness determined using FE-modeling could be improved by including detailed information about mineral distribution in trabeculae in the models.

Adult↗

PubMed2001

Quantification of first tarsometatarsal joint stiffness in hallux valgus patients.

OBJECTIVE: Comparison of the clinical mobility test of the first tarsometatarsal joint with Doppler Imaging of Vibrations measurement of the stiffness of this joint in hallux valgus patients. DESIGN: Clinical testing of first tarsometatarsal joint mobility was related to independent Doppler Imaging of Vibrations measurement of first tarsometatarsal joint stiffness. BACKGROUND: Hypermobility of the first tarsometatarsal joint has consequences for the surgical treatment of hallux valgus deformity. However, the clinical test is subjective. Doppler Imaging of Vibrations could be helpful in quantification of the stiffness of this joint. METHODS: Clinical examination of the mobility of 32 first tarsometatarsal joints in 20 hallux valgus patients was compared with Doppler Imaging of Vibrations stiffness measurements performed by an independent observer. RESULTS: There was a statistically significant relation between the clinical test and the stiffness measurement by Doppler Imaging of Vibrations. CONCLUSION: Doppler Imaging of Vibrations proves to be a method to quantify first tarsometatarsal joint stiffness and could contribute to a rational policy for the surgical treatment of hallux valgus deformity. RELEVANCE: The clinical test to establish hypermobility of the first tarsometatarsal joint is subjective. Doppler Imaging of Vibrations offers objective criteria and quantification of first tarsometatarsal joint stiffness. This provides additional information for the choice of the surgical procedure to correct hallux valgus deformity.

Biomechanical Phenomena↗

PubMed2001

Hip problems in older adults: classification by cluster analysis.

No validated classification system of hip disorders in primary care is available. This study explores whether it is possible to obtain such a classification with the method of cluster analyses. A total of 224 consecutive patients aged 50 years or older, consulting the general practitioner for pain in the hip region, and referred for X-ray investigation of the hip, underwent a standardized examination. Ward's cluster analysis with variables from history and physical examination of the hip region resulted in a classification with nine different clusters. These clusters were reproduced in 10 random subsamples and with an alternative cluster analysis. Significant relationships of various external variables (radiological and sonographic signs and variables of low-back and knee examination) with the distinctive clusters were found. Twenty of the approached experts recognized the symptoms in seven clusters as identifiable syndromes. However, further validation of the achieved classification system, especially with respect to the clinical importance, is needed before introducing it into clinical practice.

Cluster Analysis↗

PubMed2001

Tendon interposition arthroplasty versus arthrodesis for the treatment of trapeziometacarpal arthritis: a retrospective comparative follow-up study.

Long-term subjective and objective outcomes of 24 tendon interposition arthroplasties in 17 patients and 32 trapeziometacarpal (TMC) arthrodeses in 26 patients were compared retrospectively in a standardized manner. Tendon interposition arthroplasty led to complications less often (27%) than TMC arthrodesis (39%). Patients in the tendon interposition arthroplasty group reported significantly less pain, less temperature intolerance, and better thumb mobility and were more satisfied with pain symptoms than patients in the arthrodesis group. Patients undergoing tendon interposition arthroplasty had better thumb opposition, interphalangeal joint mobility, and radial and palmar TMC joint range of motion. No statistically significant differences were found in tip pinch, key pinch, and grip strength between the 2 groups. Proximal first metacarpal collapse occurred in the tendon interposition patients without affecting subjective or objective outcome. Seven of 25 patients with TMC arthrodesis had pseudarthrosis. Tendon interposition arthroplasty seems to be preferable to TMC joint arthrodesis for the treatment of TMC arthritis.

Aged↗

PubMed2001

Growth factor expression in cartilage wound healing: temporal and spatial immunolocalization in a rabbit auricular cartilage wound model.

OBJECTIVE: The ability of cartilage to regenerate following injury is limited, potentially leading to osteoarthritis. Integrative cartilage repair, necessary for durable restoration of cartilage lesions, can be regarded as a wound healing process. Little is known about the effects of growth factors regulating acute cartilage wound healing in vivo. In this study the temporal expression patterns of growth factors and proteoglycan content in cartilage wound edges in vivo were studied. DESIGN: Cartilage wounds were created in rabbit ear cartilage using a 6 mm biopsy punch. Specimens were subsequently harvested 1, 3, 7, 14 and 28 days after surgery. Paraffin sections were thionin stained to visualize proteoglycan loss and replacement. Immunohistochemical staining of TGFbeta1, TGFbeta3, IGF-1, IGF-II and FGF-2 was used to define growth factor expression at the cartilage wound sites. RESULTS: Almost no effect of cartilage wounding was observed one day after surgery. A decrease of proteoglycan content, with a maximal loss at day 7, and a subsequent restoration was observed at the wound edges. Growth factor expression increased simultaneously. Maximal immunostaining for IGF1, IGFII, FGF2 and TGF-beta3 was observed at day 7, followed by a gradual decrease. Increased expression of TGFbeta1 lasted from day 3 until day 14. CONCLUSION: We have demonstrated the ability of chondrocytes to increase growth factor expression and to restore the rapid decrease in proteoglycan content in the initial phase following acute wounding. A temporal increase in intracellular growth factor expression suggests an autocrine and/or paracrine metabolic stimulation, which can be regarded a sign of chondrocytes repair capacity.

Animals↗

PubMed2001

Mobility of the first tarsometatarsal joint in hallux valgus patients: a radiographic analysis.

Hypermobility of the first tarsometatarsal (TMT 1) joint in the sagittal plane plays a role in the etiology and treatment of the hallux valgus complex. However, objective quantification of this mobility is still a problem. We performed a radiographic analysis of TMT 1 mobility in the sagittal plane in 94 hallux valgus patients aged 15 to 65 years. We examined 94 feet with symptomatic hallux valgus deformity requiring operative correction. Excluded were patients with osteoarthritis, inflammatory diseases or previous operations on the foot. The TMT 1 mobility was tested with a clinical test and by radiographic measurement using the modified Coleman block test. The mean mobility of the TMT 1 joint in the sagittal plane in the patient group was 12.9 degrees (SD 4.80). In addition, there was a statistically significant difference between two subgroups: patients with and without clinical TMT 1 hypermobility. No correlation of TMT 1 (hyper)mobility and radiographic second ray hypertrophy was found. This simple method can produce additional information to the clinical TMT 1 hypermobility test in the sagittal plane.

Adolescent↗

PubMed2001

Mechanical consequences of bone loss in cancellous bone.

The skeleton is continuously being renewed in the bone remodeling process. This prevents accumulation of damage and adapts the architecture to external loads. A side effect is a gradual decrease of bone mass, strength, and stiffness with age. We investigated the effects of bone loss on the load distribution and mechanical properties of cancellous bone using three-dimensional (3D) computer models. Several bone loss scenarios were simulated. Bone matrix was removed at locations of high strain, of low strain, and random throughout the architecture. Furthermore, resorption cavities and thinning of trabeculae were simulated. Removal of 7% of the bone mass at highly strained locations had deleterious effects on the mechanical properties, while up to 50% of the bone volume could be removed at locations of low strain. Thus, if remodeling would be initiated only at highly strained locations, where repair is likely needed, cancellous bone would be continuously at risk of fracture. Thinning of trabeculae resulted in relatively small decreases in stiffness; the same bone loss caused by resorption cavities caused large decreases in stiffness and high strain peaks at the bottom of the cavities. This explains that a reduction in the number and size of resorption cavities in antiresorptive drug treatment can result in large reductions in fracture risk, with small increases in bone mass. Strains in trabeculae surrounding a cavity increased by up to 1,000 microstrains, which could lead to bone apposition. These results give insight in the mechanical effects of bone remodeling and resorption at trabecular level.

Bone Remodeling↗

PubMed2001

A three-dimensional simulation of age-related remodeling in trabecular bone.

After peak bone mass has been reached, the bone remodeling process results in a decrease in bone mass and strength. The formation deficit, the deficit of bone formation compared with previous resorption, results in bone loss. Moreover, trabeculae disconnected by resorption cavities probably are not repaired. The contributions of these mechanisms to the total bone loss are unclear. To investigate these contributions and the concomitant changes in trabecular architecture and mechanical properties, we made a computer simulation model of bone remodeling using microcomputed tomography (micro-CT) scans of human vertebral trabecular bone specimens. Up to 50 years of physiological remodeling were simulated. Resorption cavities were created and refilled 3 months later. These cavities were not refilled completely, to simulate the formation deficit. Disconnected trabeculae were not repaired; loose fragments generated during the simulation were removed. Resorption depth, formation deficit, and remodeling space were based on biological data. The rate of bone loss varied between 0.3% and 1.1% per year. Stiffness anisotropy increased, and morphological anisotropy (mean intercept length [MIL]) was almost unaffected. Connectivity density increased or decreased, depending on the remodeling parameters. The formation deficit accounted for 69-95%, disconnected trabeculae for 1-21%, and loose fragments for 1-17% of the bone loss. Increasing formation deficit from 1.8% to 5.4% tripled bone loss but only doubled the decrease in stiffness. Increasing resorption depth from 28 to 56 microm slightly increased bone loss but drastically decreased stiffness. Decreasing the formation deficit helps to prevent bone loss, but reducing resorption depth is more effective in preventing loss of mechanical stiffness.

Adult↗

PubMed2001

The bone block procedure in recurrent posterior shoulder instability.

We analyzed the results of eleven shoulders in ten patients who had a bone block procedure for recurrent posterior shoulder instability after extensive conservative treatment had failed. Five patients had posterior instability with additional laxity in another direction (UPI+), and five patients had unidirectional posterior instability without additional laxity (UPI-). After a median follow-up of 72 (43-102) months there was no recurrent posterior instability in the UPI-group (100% success), but the recurrence rate in the UPI+ group was high (20% success). We concluded from these results that a bone block procedure is not sufficient to treat recurrent posterior shoulder instability in unidirectional posterior instability with additional laxity but it seems to be a good method to treat unidirectional posterior instability without additional laxity.

Adolescent↗

PubMed2000

Tissue-engineered cartilage using serially passaged articular chondrocytes. Chondrocytes in alginate, combined in vivo with a synthetic (E210) or biologic biodegradable carrier (DBM).

In vitro multiplication of isolated autologous chondrocytes is required to obtain an adequate number of cells to generate neo-cartilage, but is known to induce cell-dedifferentiation. The aim of this study was to investigate whether multiplied chondrocytes can be used to generate neo-cartilage in vivo. Adult bovine articular chondrocytes, of various differentiation stages, were suspended in alginate at densities of 10 or 50 million/ml, either directly after isolation (P0) or after multiplication in monolayer for one (P1) or three passages (P3). Alginate with cells was seeded in demineralized bovine bone matrix (DBM) or a fleece of polylactic/polyglycolic acid (E210) and implanted in nude mice for 8 weeks. The newly formed tissue was evaluated by Alcian Blue and immunohistochemical staining for collagen type-II and type-I. Structural homogeneity of the tissue, composed of freshly isolated as well as serially passaged cells, was found to be enhanced by high-density seeding (50 million/ml) and the use of E210 as a carrier. The percentage of collagen type-II positive staining P3-cells was generally higher when E210 was used as a carrier. Furthermore, seeding P3-chondrocytes at the highest density (50 million/ml) enhanced collagen type-II expression. This study shows promising possibilities to generate structurally regular neo-cartilage using multiplied chondrocytes in alginate in combination with a fleece of polylactic/polyglycolic acid.

Alcian Blue↗

PubMed2000

Fixation-dependent immunolocalization shift and immunoreactivity of intracellular growth factors in cartilage.

The effects of fixation on immunolocalization and immunoreactivity in cartilage tissues were studied using monoclonal antibodies against peptides that can effectively stimulate chondrocytes in vitro and have been shown to play a role in musculoskeletal tissue regeneration: transforming growth factor beta1, transforming growth factor beta3, insulin-like growth factor I, insulin-like growth factor II and fibroblast growth factor 2. Paraffin sections fixed in buffered formalin, buffered paraformaldehyde, Carnoy and methacarn, as well as cryosections, were tested. A strong immunoreaction was observed in tissue fixed in formaldehyde-based fixatives, with a resemblance to that in cryopreserved tissues. Immunoreactivity was reduced in alcohol-fixed tissues. Furthermore, a striking intracellular immunolocalization shift from cytoplasm to nucleus was observed using alcohol-based fixatives as compared to cryopreserved or formaldehyde-based fixatives. We concluded that, for the detection and localization of growth factors in cartilage tissues, fixation in buffered formalin or paraformaldehyde is optimal.

Animals↗

PubMed2000

Impaction bone-grafting of severely defective femora in revision total hip surgery: 21 hips followed for 41-85 months.

We performed a prospective study to evaluate the application of impacted allograft bone particles at revision surgery of severely defective femora. According to the Endo-Klinik classification, 21 hips had grade III or IV femoral defects, of which 4 had a preoperative fracture. No femoral re-revisions had been necessary after a mean follow-up of 60 (41-85) months. The mean Harris Hip Score improved by 39 points to 78 points. 2 fractures occurred postoperatively, 1 of which needed reoperation with osteosynthesis. 1 patient needed a closed reduction after dislocation. 4 stems showed significant subsidence (> 10 mm) in the follow-up radiographs. In total hip revision surgery, even severely damaged femora can be successfully treated by impaction allografting.

Adult↗

PubMed2000

Sonography for hip joint effusion in adults with hip pain.

OBJECTIVE: To study the prevalence of ultrasonic hip joint effusion and its relation with clinical, radiological and laboratory (ESR) findings in adults with hip pain. METHODS: Patients (n = 224) aged 50 years or older with hip pain, referred by the general practitioner for radiological investigation, underwent a standardised examination. The distance between the ventral capsule and the femoral neck, an increase in which represents joint effusion, was measured sonographically. Joint effusion was defined in three different ways: "effusion" according to Koski's definition, "major effusion", and "asymmetrical effusion" based on only individual side differences. RESULTS: "Effusion" was present in 80 (38%), "major effusion" in 20 (9%), and "asymmetrical effusion" in 47 (22%) patients. Pain in the groin or medial thigh, pain aggravated by lying on the side, decreased extension/internal rotation/abduction/flexion, painful external rotation, and pain on palpation in the groin showed a significant relation (adjusted for age and radiological osteoarthritis of the hip) with ultrasonic hip joint effusion. "Major effusion" showed a significant relation with an increased ESR. When patients with bilateral pain and increased ESR were excluded, a side difference in the range of motion of extension of the hip was shown to be a good predictor for "asymmetrical effusion" (positive predictive value: 71%, negative predictive value: 80%). CONCLUSION: This study showed a relatively high prevalence of ultrasonic joint effusion in adults with hip pain in general practice. Furthermore the results indicate a relation between joint effusion and clinical signs.

Aged↗

PubMed1999

[Distorsion or rupture of ankle ligaments?].

In the Netherlands, almost 500,000 patients visit a physician each year because of an ankle inversion trauma. Most people are seen by a general practitioner, but a considerable number go directly to an emergency department. Recently a nation-wide accepted strategy for diagnosis and treatment of these lesions was formulated. This strategy includes the use of the Ottawa ankle rules, a second physical examination after four to five days if there is severe swelling of the ankle and functional treatment with inelastic tape bandage or brace application in case of an established rupture of the lateral band complex. At present, however, the efficacy of a second physical examination in primary health care has not been analysed and the economic consequences of the new strategy are unknown. From a scientific point of view none of the types of conservative treatment is preferable to another. Further scientific studies are needed.

Ankle Injuries↗

PubMed1999

Mobility of the first tarsometatarsal joint in relation to hallux valgus deformity: anatomical and biomechanical aspects.

Hypermobility of the first tarsometatarsal (TMT 1) joint is suggested to be an important factor in the cause and progression of hallux valgus deformity. Hypermobility of the TMT 1 joint is tested clinically in the sagittal plane, but an important deformation also exists in the transversal plane: metatarsus primus varus. This in vitro study was undertaken to investigate the relation between the mobility of the TMT 1 joint in these two planes and to investigate the correlation of the mobility with morphological variables. A second aim was to study the possible stabilizing effect of the tibialis anterior muscle, flexor hallucis longus muscle, and peroneus longus muscle on the TMT 1 joint. Nine embalmed human specimens were tested under standardized conditions. A 30-N force was applied to the head of the first metatarsal (MT 1) to pull in either the dorsal or medial direction. To simulate muscle force, 21 N was applied to the three tendons: all seven possible combinations of muscle action were tested in each plane of motion. Angular displacements were measured using 2-dimensional LED video registration. TMT 1 mobility is a relevant factor in MT 1 mobility in the sagittal and transversal planes, the peroneus longus has a stabilizing effect on this joint, and the effect of the flexor hallucis longus on this joint is different in both planes. When considering a Lapidus procedure for surgically correcting a hallux valgus, the mobility of MT 1 in the transversal plane should also be assessed, but so far no objective clinical test in this plane has been described.

Aged↗

PubMed1999

Optimization of chondrocyte expansion in culture. Effect of TGF beta-2, bFGF and L-ascorbic acid on bovine articular chondrocytes.

In vitro multiplication of isolated chondrocytes is needed to repair articular cartilage defects with autologous material. In this study we used monolayer cultures of bovine articular chondrocytes. The effect of transforming growth factor beta-2, basic fibroblast growth factor or L-ascorbic acid on cell multiplication, in the presence of 10% fetal calf serum, was measured in primary culture, the third and tenth passage. TGF beta-2 stimulated the proliferation of chondrocytes in the primary culture and L-ascorbic acid stimulated in the third passage. On the basis of these results, we chose an optimal addition scheme in which TGF beta-2 was added in primary culture and first passage, followed by addition of L-ascorbic acid in the second and third passage; this resulted in a 7-fold increase in cell number compared to the control group, in about 4 weeks. Our findings stress the importance of adding the right growth factor at the right moment. Collagen type II expression was lost after the third passage, in the control as well as in the experimental condition. The ability to produce hyaline cartilage specific matrix components is essential, if multiplied cells are to be used to repair cartilage defects.

Animals↗

PubMed1999

Tennis elbow, natural course and relationship with physical activities: an inquiry among physicians.

BACKGROUND: The main purposes of the study were to answer the following two questions: is a restrictive therapeutic management in case of tennis elbow (TE) better or worse than a regular therapeutic approach and do racket sports and other physical activities influence the risk to get TE and to what extent. METHODS DESIGN: Cross-sectional study by means of a postal questionnaire. The impression was verified that physicians are reserved about medical interventions when treating themselves for tennis elbow. The frequency of therapeutic measures and their results were compared with data reported in literature. Physical activities of physicians who had TE were compared with those of physicians who never had TE. SETTING: Physicians who attended postgraduate courses on diagnosis and treatment in orthopedic medicine from 1984 to 1992. PARTICIPANT: 72 physicians who had TE and 266 with no history of TE. MEASURE: The study is based on self-assessment of therapeutic approaches and their results, reported physical activities at the onset of TE and at the moment of the inquiry. By a team of experts the grade of grasping and/or dorsiflexion of the physical activities was classified. RESULTS: Compared with patients in general practice, physicians treating themselves for TE were more restrictive to use NSAID's, ointments or local steroid injections or to consult a specialist. No-one was treated with surgery and no-one interrupted her/his work because of TE. In all but two of the 72 cases the TE resolved within two years. The odds ratio for TE for playing racket sports versus not playing racket sports was 2.8 (95% confidence interval 1.64-4.82). The odds ratio for activities with low-grade grasping and/or dorsiflexion versus "no sports or hobbies" was 0.11 (0.02-0.50). CONCLUSIONS: Absence from work and therapeutic measures for TE are (in physicians) not necessary for a good result on the long term. Playing racket sports increases the risk to get TE by a factor of 2.8. Performing weekly activities with low grade grasping and/or dorsiflexion of the wrist may have a protective effect against developing tennis elbow.

Adult↗